\documentclass{article}
\usepackage[x11names, rgb]{xcolor}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{snakes,arrows,shapes}
\usepackage{amsmath}
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\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{0pt}%
\usetikzlibrary{automata}%

\begin{document}
\pagestyle{empty}
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\enlargethispage{100cm}
% Start of code
% \begin{tikzpicture}[anchor=mid,>=latex',join=bevel,]
\begin{tikzpicture}[>=latex',join=bevel,]
  \pgfsetlinewidth{1bp}
\Huge%
\pgfsetcolor{black}
 % % Edge: q6 -> q7
%  \draw [->] (32bp,88bp) .. controls (32bp,76bp) and (32bp,60bp)  .. (32bp,36bp);
%  \draw (70bp,62bp) node[auto] {$\overline{Reply}$};
  % Edge: q5 -> q6
  \draw [->] (104bp,176bp) .. controls (104bp,166bp) and (104bp,153bp)  .. (104bp,142bp) .. controls (104bp,139bp) and (104bp,137bp)  .. (104bp,124bp);
  \draw (120bp,150bp) node[auto] {$...$};
 % % Edge: q5 -> q6
%  \draw [->] (32bp,176bp) .. controls (32bp,164bp) and (32bp,148bp)  .. (32bp,124bp);
%  \draw (30bp,150bp) node[auto] {$...$};
  % Edge: q2 -> q4
  \draw [->] (65bp,353bp) .. controls (59bp,340bp) and (51bp,323bp)  .. (40bp,299bp);
  \draw (43bp,326bp) node[auto] {$\tau$};
  % Edge: q2 -> q3
  \draw [->] (79bp,352bp) .. controls (83bp,340bp) and (89bp,323bp)  .. (98bp,300bp);
  \draw (100bp,326bp) node[auto] {$\tau$};
  % Edge: q4 -> q5
  \draw [->] (32bp,264bp) .. controls (32bp,252bp) and (32bp,236bp)  .. (32bp,212bp);
  \draw (-15bp,238bp) node[auto] {$\overline{Reply}$};
  % Edge: q3 -> q6
  \draw [->] (104bp,264bp) .. controls (104bp,252bp) and (104bp,236bp)  .. (104bp,212bp);
  \draw (150bp,238bp) node[auto] {$\overline{Invoke}$};
  % Edge: q1 -> q2
  \draw [->] (73bp,440bp) .. controls (73bp,428bp) and (73bp,412bp)  .. (73bp,388bp);
  \draw (120bp,414bp) node[auto] {$\overline{Invoke}$};
  % Edge: q0 -> q1
  \draw [->] (73bp,528bp) .. controls (73bp,516bp) and (73bp,500bp)  .. (73bp,476bp);
  \draw (118bp,502bp) node[auto] {$Receive$};
  % Node: q0
\begin{scope}
  \draw [state] (73bp,546bp) ellipse (27bp and 18bp);
  \draw (73bp,546bp) node {$q_{0}$};
\end{scope}
  % Node: q7
\begin{scope}
  \draw [state] (104bp,106bp) ellipse (27bp and 18bp);
  \draw (104bp,106bp) node {$...$};
\end{scope}
  % Node: q5
\begin{scope}
  \draw [state] (32bp,194bp) ellipse (27bp and 18bp);
  \draw (32bp,194bp) node {$q_{5}$};
\end{scope}
  % Node: q2
\begin{scope}
  \draw [state] (73bp,370bp) ellipse (27bp and 18bp);
  \draw (73bp,370bp) node {$q_{2}$};
\end{scope}
  % Node: q4
\begin{scope}
  \draw [state] (32bp,282bp) ellipse (27bp and 18bp);
  \draw (32bp,282bp) node {$q_{4}$};
\end{scope}
  % Node: q6
\begin{scope}
  \draw [state] (104bp,194bp) ellipse (27bp and 18bp);
  \draw (104bp,194bp) node {$q_{6}$};
\end{scope}
  % Node: q3
\begin{scope}
  \draw [state] (104bp,282bp) ellipse (27bp and 18bp);
  \draw (104bp,282bp) node {$q_{3}$};
\end{scope}
  % Node: q1
\begin{scope}
  \draw [state] (73bp,458bp) ellipse (27bp and 18bp);
  \draw (73bp,458bp) node {$q_{1}$};
\end{scope}
%
\end{tikzpicture}
% End of code

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\end{document}
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